Optical support table



July 4, 1967 p MCPHERSON 3,329,105

OPTI CAL SUPPORT TABLE Filed June 5, 1966 l NVEN'l "OR. Palm MJJZFEVZfW/b BY United States Patent 3,329,105 OPTICAL SUPPORT TABLE PaulM. McPherson, Acton, Mass., assignor to McPherson Instrument Corp.,Acton, Mass., a corporation of Massachusetts Filed June 3, 1966, Ser.No. 555,057 3 Claims. (Cl. 108-144) This invention relates to the fieldof support tables, and more particularly to tables used for moving andstabilizing extremely sensitive optical apparatus.

Support tables now in use conventionally have four legs with wheels andfour stabilizers by means of which the Wheels are raised equally off theground for stable support. Lever means or hydraulic means are used tosimultaneously actuate the stabilizers to elevate the table. Thesefeatures, while adequate for many purposes, prove unsuitable for generaluse with sensitive optical apparatus which must be precisely levelled onfioors customarily a bit uneven, and which must be elevatable to diverseworkin heights for use with other apparatus. Moreover, the means usedoften do not work smoothly, but permit apparatus to be bumped or jarredas it is raised or lowered.

Accordingly, the principal objects of the present invention are toprovide a support table which olfers firm and stable support for opticalapparatus, which is easily and precisely levelled without loss ofstability during levelling, which is elevatable to diverse workingheights, which can be lowered or raised smoothly and without jarring orbumping, and which, when mobile, safely and stably transports heavy andcostly optical apparatus.

Briefly summarized, the invention is a mobile optical levelling tablehaving a bench structure upon which the optical apparatus is to beplaced, and a first set of legs attached to and depending from the benchstructure. These legs have casters at their lower ends for mobility. Inaddition, a second set of three triangularly spaced hollow legs isattached to the bench structure such that the center of gravity of thetable is located a substantial distance inside the triangle defined bythe legs.'In each of these hollow legs there is an independentlyadjustable screw-jack means which is extensible downwardly from aposition above the casters to a position below the casters, whereby thetable may be smoothly raised and precisely levelled, or loweredcarefully upon the casters. Each screw-jack means extends into a hollowleg a major part of the length of the hollow leg, so that the table hasa wide range of possible elevations.

For the purpose of illustration a typical embodiment of the invention isshown in the accompanying drawing in which:

FIG. 1 is an isometric view showing the table supported for transport bythe legs with casters, the screw-jack means being elevated above thecasters;

FIG. 2 is an isometric view showing the table supported by-thescrew-jack means, the screw-jack means being extended below the casters;

FIG. 3 is a plan view of the table; and

FIG. 4 is a section on line 4-4 of FIG. 3.

In the particular embodiment of the invention chosen for the purpose ofillustration, the table has a bench structure 1 comprising a flat topportion 2, a fiat bottom portion 3, and a peripheral skirt 4 extendingbetween the top and the bottom portions. As shown in FIGS. 1 or 2,portions of the top portion, the bottom portion and the peripheral skirtare removed to reduce the weight of the bench structure.

Attached to and depending from the bench structure 1 is a first set ofthree spaced legs, 1a, 2a, 3a. This first set of legs is spaced to forma triangle; the leg 1a being centrally located at one end of the benchstructure 1, and the legs 2a and 3a being located at the corners of theopposite end of the bench structure.

As shown in FIG. 4, each leg 1a, 2a or 3a comprises a hollow tube 5which fits through a circular hole provided in the bottom portion 3 ofthe bench structure and abuts the top portion 2. Tack welds secure thetube 5 to the top and bottom portions of the bench structure. In thelower end of the tube 5, and secured thereto by welding or the like, isa cylindrical block 6, to which a swivelling caster 7 is fastened.

-The first set of legs 1a, 2a and 3a stably supports the table when itis transporting optical apparatus. As shown in FIG. 3, the center ofgravity of the table is substantially within the projection of atriangle defined by the first set of legs. To further increase stabilityduring transport of apparatus, it is preferable that the first set oflegs be susbtantially shorter than the intended operating height of thetable. This provides a low center of gravity for the table and apparatuswhen it is mobile and permits safe negotiation of ramps and unevensurfaces without danger of tipping.

Also attached to the bench structure 1 and depending therefrom is asecond set of three spaced legs 1b, 2b and 3b, terminating above thefirst set of legs. This second set of legs is triangularly spaced asshown in FIGS. 1, 2 or 3, the leg 1b being centrally located between thelegs 2a and 3a at one end of the bench structure 1, and the legs 2b and3b being located at the corners at the opposite end of the benchstructure. As shown in FIG. 3, the center of gravity of the table alsolies substantially within the triangle defined by this second set oflegs, so that either set of legs supports the apparatus stably.

As shown in FIG. 4, each leg 1b, 2b or 3b comprises a hollow tube 9,fitting through a hole provided in the bottom portion of the benchstructure, and abutting the top .portion 2 of the bench structure. Tackwelds secure the tube 9 to the bench structure. A cylindrical plug 10 isinserted in the upper end of the tube 9 and secured thereto. A hole 11,threaded to receive a machine screw, is provided in the plug 10 andupper portion 2 of the bench structure.

A plurality of cylindrical guide blocks 12 is spaced lengthwise of theinterior of the tube 9 and secured thereto by welding or the like.

In each of the hollow legs 1b, 2b and 3b, a screwjack 13 threada-blyengages the guide block 12 so as to be adjustable axially in the tube 9.Each screw-jack extends into a hollow leg a major part of the length ofthe hollow leg. This permits the table to be raised a substantialdistance and provides a wide range of operating heights. At the lowerend of the screw-jack 13 a ball-and-socket levelling pad 14 is providedto obtain firm support on uneven surfaces. Just above the levelling pad,gripping means 15 are provided, whereby the screwjack may be rotated andadjusted axially with a wrench or the like. Alternatively, a lever maybe attached to the screw-jack to facilitate its rotation and adjustment.

As shown in FIGS. 1 and 4, the screw jacks 13 are extensible upwardly toan elevated position above the bottoms of the casters 7 on the first setof legs. When so elevated, the table is mobile. As shown in FIG. 2, thescrew-jacks are also extensible downwardly to a lowered positionsubstantially below the casters, thus raising the table to a desiredworking height. As described, each screw-jack means is independently andcontinuously adjustable, which permits the table to be easily andprecisely levelled. The provision of exactly three screw-jack means,spaced triangularly about the center of gravity of the table, assuresthat the table will remain stable during the levelling process. And thecontinuous, even motion Q of the screw-jacks assures that sensitiveapparatus will not be jarred or bumped as the table is raised orlowered.

It should be understood that the present disclosure is for the purposeof illustration only and that this invention includes all modificationsand equivalents which fall within the scope of the appended claims.

I claim:

1. A mobile optical levelling table comprising (a) a bench structure (b)a first set of least three spaced legs attached to and depending fromthe bench structure, said legs having casters at their lower ends,

(c) a second set of three spaced hollow legs fixed to and depending fromthe bench structure, each of said legs terminating above the first setof legs,

(d) screw-jack means in each of said hollow legs and adjustablyextensible downwardly out of said hollow legs from an elevated positionabove said casters to a lowered position below said casters, the centerof gravity of said table being located a substantial distance inside theprojection of a triangle defined by said three screw-jack means, eachscrew-jack means extending into a hollow leg a major part of the lengthof the hollow leg, and each said screw-jack means being independentlyadjustable,

whereby said table may safely stably transport heavy optical apparatuswhen on said casters, and thereafter may be raised by said screw-jackmeans to operating height and stably levelled.

2. A mobile optical levelling table comprising (a) a bench structure;

(b) a first set of three triangularly spaced legs attached to anddepending from the bench structure, the center of gravity of the benchstructure lying a substantial distance within the triangle defined bythe first set of legs, each of the first set of legs compris- (1) a tubesecured at one end to the bench structure; and

(2) a swivelling caster fastened to the opposite end of the tube,whereby the table may safely stably transport heavy optical apparatuswhen on the casters;

(c) a second set of three triangularly spaced vertical legs attached toand depending from the bench struc- 4 ture, the center of gravity of thebench structure lying a substantial distance within the triangle definedby the second set of legs, each of the second set of legs comprising'(1) a tube secured at one end to the bench structure and terminatingabove the first set of legs;

(d) screw-jack means in each of the second set of legs and independentlyadjustably extensible downwardly out of the legs from an elevatedposition above the casters to a lowered position below the casters, eachscrew-jack means comprising (1) a plurality of guide blocks spacedlengthwise in the leg and secured therein;

(2) a screw-jack threadably engaging the guide blocks and extending amajor part of the length of the leg; and

(3) a levelling pad secured to the lower end of the screw-jack, wherebythe table may be raised by the screw-jacks to operating height andstably levelled.

3. A mobile optical levelling table according to claim 2 wherein thebench structure comprises (a) a flat top portion;

(b) a fiat bottom portion; and

(c) a peripheral skirt extending between the top and bottom portions andsecured thereto;

and wherein the tubes of both sets of legs extend through holes providedin the bottom portion and abut the top portion, being secured to the topand bottom portions by welds.

References Cited UNITED STATES PATENTS 198,576 12/1877 DAmore 182-l7 X204,893 6/1878 Gibbons 18217 X 2,360,999 10/1944 Wyen 182-l7 3,232,3772/1966 Smith 182l7 X FOREIGN PATENTS 280,126 4/ 1952 Switzerland.

DAVID J. WILLIAMOWSKY, Primary Examiner.

FRANK B. SHERRY, Examiner.

G. O. FINCH, Assistant Examiner.

1. A MOBILE OPTICAL LEVELLING TABLE COMPRISING (A) A BENCH STRUCTURE (B)A FIRST SET OF LEAST THREE SPACED LEGS ATTACHED TO AND DEPENDING FROMTHE BENCH STRUCTURE, SAID LEGS HAVING CASTERS AT THEIR LOWER ENDS, (C) ASECOND SET OF THREE SPACED HOLLOW LEGS FIXED TO AND DEPENDING FROM THEBENCH STRUCTURE, EACH OF SAID LEGS TERMINATING ABOVE THE FIRST SET OFLEGS, (D) SCREW-JACK MEANS IN EACH OF SAID HOLLOW LEGS AND ADJUSTABLYEXTENSIBLE DOWNWARDLY OUT OF SAID HOLLOW LEGS FROM AN ELEVATED POSITIONABOVE SAID CASTERS TO A LOWERED POSITION BELOW SAID CASTERS, THE CENTEROF GRAVITY OF SAID TABLE BEING LOCATED A SUBSTANTIAL DISTANCE INSIDE THEPROJECTION OF A TRINAGLE DEFINED BY SAID THREE SCREW-JACK MEANS, EACHSCREW-JACK MEANS EXTENDING INTO A HOLLOW LEG A MAJOR PART OF THE LENGTHOF THE HOLLOW LEG, AND EACH SAID SCREW-JACK MEANS BEING INDEPENDENTLYADJUSTABLE, WHEREBY SAID TABLE MAY SAFELY STABLY TRANSPORT HEAVY OPTICALAPPARATUS WHEN ON SAID CASTERS, AND THEREAFTER MAY BE RAISED BY SAIDSCREW-JACK MEANS TO OPERATING HEIGHT AND STABLY LEVELLED.